Photocopy fraud protection is an important issue for many businesses and government agencies. Methods for limiting the distribution and unauthorized photocopying of sensitive documents include printing a limited number of documents with each original document assigned to an intended recipient. Original documents may be sequentially numbered and bear the recipients' names on the title page or in the header or footer on each page of the document. Some disadvantages of such methods are that an original document can be photocopied without a title page and a strip of paper can be used to mask off header or footer information during photocopying.
Another method for limiting the distribution and unauthorized photocopying of sensitive documents includes printing such documents on pre-prepared, copy-protected print media (e.g., paper). Such media typically includes background information, such as a warning message, encoded or embedded into a security watermark that can be mostly unnoticeable to a casual observer. If a photocopy is made of such a document printed on copy-protected paper, however, the background information or security watermark becomes prominently displayed on the photocopy. Therefore, the warning message becomes noticeable to even a casual observer if the document is photocopied. Details of such security watermarks are well-known to those skilled in the art and can be found in, for example, U.S. Pat. No. 5,788,285 to Wicker, U.S. Pat. No. 6,139,066 to Mowry et al., and U.S. Pat. No. 6,414,757 to Salem.
Use of such pre-prepared, copy-protected paper in conventional printing devices can have disadvantages, however. For example, tracing an unauthorized photocopy back to a recipient of an original document is difficult if the recipient's name is not on the photocopy. Recipients may tend to take less care in managing such documents knowing that they will not be linked to unauthorized copies. Another disadvantage with this method is that a strip of paper can be used to mask off warnings in the header or footer during photocopying. Yet another disadvantage is that use of such copy-protected paper is labor-intensive. Each use of the paper requires that a printer be specially loaded with the paper and then unloaded when printing on the special paper is completed.